Periodic cleaning and sanitizing in the food process industry is a regimen mandated by law and rigorously practiced to maintain the exceptionally high standards of food hygiene and shelf-life expected by today's consumer. Residual food soil left on food contact equipment surfaces can harbor and nourish the growth of opportunistic pathogen and food spoilage microorganisms. These pathogen and microorganisms can contaminate foodstuffs processed in close proximity to the residual soil. Insuring protection of the consumer against potential health hazards associated with food borne pathogens and toxins requires diligent cleaning and soil removal from any surface that contacts the food product directly or any surface that is associated with the processing environment.
Because of food quality concerns and public health pressures, the food processing industry has attained a high standard of practical cleanliness and sanitation. This has not been achieved without great expense, and there is considerable interest in more efficient and less costly technology to effectuate this goal.
The food process industry has come to rely on detergent efficiency in removing food soil from surfaces that contact food products. A major challenge of detergent development for the food process industry includes (1) the successful removal of food soils that are resistant to conventional treatment and (2) the elimination of chemicals that are not compatible with food processing. One such food soil is protein, and two such chemicals are chlorine (or chlorine yielding compounds) and quaternary ammonium compounds, both of which can be incorporated into detergent compositions or can be added separately to cleaning programs for protein removal.
Protein soil residues, often called protein films, occur in all food processing industries but the problem is heightened in the dairy industry because dairy products are among the most perishable of major foodstuffs and any soil residues have serious quality consequences. Protein soil residues are common in the fluid milk and milk by-products industry, including dairy farms. This is no surprise because protein constitutes approximately 27% of natural milk solids, (Harper, W. J., Milk Components and Their Characteristics, Dairy Technology and Engineering (editors Harper, W. J. and Hall, C. W.) pp. 18-19, The AVI Publishing Company, Westport, 1976).
Hypochlorite is well-known as a proteinaceous cleaning aid and is often used as an ingredient in continuous in-place (CIP) alkaline detergent compounds was found to help remove protein film. As a result, the food process industry currently employs this technology. Chlorine degrades proteins by the oxidative cleavage and hydrolysis of the peptide bond, which breaks apart large protein molecules into smaller peptide chains. The conformational structure of the protein disintegrates, dramatically lowering the binding energies, and effecting desorption from the surface, followed by solubilization or suspension into the cleaning solution.
The use of chlorinated detergent solutions in the food process industry, however, is not without problems. Corrosion is a constant concern, as is the degradation of polymeric gaskets, hoses, and appliances. Available chlorine concentrations must initially be at least 75 ppm, and preferably, 100 ppm for optimum protein film removal. At concentrations of available chlorine less than 50 ppm, protein soil build-up is enhanced by formation of insoluble, adhesive chloro-proteins. Chlorine concentrations are not easy to maintain or analytically discern in detersive solutions. The effectiveness of chlorine on protein soil removal diminishes as solution temperature and pH decrease, lower temperatures affecting reaction rate, and lower pH favoring chlorinated moieties other than the OCl.sup.- peptizing species. High temperature and high pH are therefore desirable for peptizing proteins in general. However, in the case of milk proteins, high temperature and high pH lead to denaturing the protein making its removal more difficult. In addition, the high temperatures associated with cleaning heat transfer, food-contact surfaces, typically greater than 165.degree. F., causes off-gassing of chlorine from the chlorinated alkaline cleaner leading to corrosion of the stainless steel equipment. The problems associated with the use and applications of chlorine-containing cleaning agents in the food processing industry have been known and tolerated for decades. However, no safe, effective, and relatively inexpensive alternative has been advanced by the detergent manufacturers.
The chlorine releasing compounds (e.g., organochloro compounds) pose an additional problem. There is a growing public concern over the health and environmental impacts of chlorine and organochlorines. Whatever the merits of the scientific evidence regarding carcinogenicity, there is little argument that organohalogen compounds are persistent and bioaccumulative; and that many of these compounds pose greater non-cancer health effects (e.g., endocrine, immune, and neurological problems) principally in the offspring of exposed humans and wildlife, at extremely low exposure levels. It is, therefore, prudent for the food process industry and their detergent suppliers to focus on finding cleaning compositions that do not include chlorine releasing agents.
The other well-known cleaning aid, quaternary ammonium compounds, do not have the health, environmental, and application difficulties of chlorinated detergents. However, quaternary ammonium compounds are highly substantive to metal surfaces and often have residual kill activity. This property has resulted in the deactivation of cheese-making cultures that come into contact with the routinely cleaned surface. As such, these quaternary ammonium compounds are not suitable as components of cleansing or sanitizing solutions for surface areas that may contact cheese-making cultures.
A substantial need therefore exists for novel, safe, and effective compositions that are suitable for removing proteinaceous material in the food process industry. The composition should not include chlorine, or a chlorine containing compound. In addition, the composition should not include a compound that has residual kill activity in the dairy industry.